Diseases of the Respiratory Tract

By Elena Connolly

“There is evidence that the genetic identity of respiratory pathogen isolates recovered from bronchoalveolar lavage fluid of elderly people who are hospitalized or institutionalized is the same as isolates from their dental plaques” JADA, Vol. 138 http://jada.ada.org September 2007 30S

There is an emerging correlation between oral health and the contraction of respiratory infection.The unique proximity of the oral cavity and respiratory tract and lungs has made this connection the subject of much inquiry. Respiratory disease comes in many forms including community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP), the related ventilator-associated pneumonia (VAP) andNursing Home Acquired Pneumonia (NHAP), and chronic bronchitis—each of which being linked to periodontitis.

Pneumonia is an infection of the lungs caused by virus, bacteria, fungi, or parasites. Bacterial pneumonia is particularly dangerous and can have devastating residual effects ranging from higher medical costs, to decline of quality of life, and mortality.

CAP is relatively common and affects about 4 million people in the United States per year. It accounts for 600,000 hospitalizations, 64 million days of restricted activity, and 45,000 deaths per year . Development of CAP is especially problematic for seniors. One study evaluated the one year mortality rate of 158,960 elderly CAP patients compared to 794,333 control subjects hospitalized for something other than CAP. They found that the single-year mortality rate for CAP patients was 40.9% verses only about 29% for the control group. CAP poses a real health threat to those affected, especially those higher in age .

Aspiration pneumonia is initiated by the inhalation of oropharygeal secretions colonized by pathogenic bacteria. This type is very common in a nursing home setting. It poses the highest risk under circumstances if increased aspirate volume, and especially in cases of elevated organism levels found in the aspirate.

HAP is commonly characterized by pneumonia that appears within 48 hours of being hospitalized. There is a related type, nursing home associated pneumonia (NHAP), whose high mortality rate makes it very important to evaluate. It is also a very common cause for hospitalizations among the elderly. One bout with HAP can add up to 6 extra days of hospitalization and thousands of dollars in medical costs. The mortality rate can be as high as 25% .

NHAP is specific to the nursing home or institutionalized setting. One study of 666 nursing home patients found that respiratory infections accounted for about half of all infections among the population (47%) . Respiratory disease is the leading cause of acute hospitalizations, about 21%, and NHAP can account for up to 45% of all respiratory related hospital admissions .

There are several means of linking oral health to pneumonia. For one, the oral cavity can serve as a reservoir for bacteria. Dental plaque harbors many of the same bacteria that cause pneumonia. This dental plaque is also involved in the development of periodontal disease. Bacteria can be easily released from this plaque into oral secretions, and aspirated into the lungs. Those at the highest risk include patients who have lost the ability to swallow, those with limited salivary flow, or decreased cough reflex.

In fact, aspiration of saliva has been shown as the main avenue for bacteria to enter the lungs among the institutionalized elderly . Another study involving 613 nursing home patients showed a strong association between difficulty swallowing and poor oral health and the development of pneumonia.

The detachment associated with periodontitis leaves pockets where bacteria can easily colonize leads to increased levels of respiratory pathogens, which may serve to promote pneumonia.

Further studies have shown a distinct relationship between the bacteria found in the oral cavity and the bacteria found in an infected lung. Strains of bacteria recovered from lung fluid were compared to those found in the dental plaque of a critically ill patient. Using a pulse-field gel electrophoresis, it was determined that 9 respiratory pathogens were genetically identical to the corresponding bacteria found in the dental plaque . “This is the first study to establish unequivocally a link between dental hygiene and respiratory infection,” said Dr. Ali A. El-Solh, the leading researcher on the study.

The severity of respiratory disease has been shown to be quelled by oral intervention. For example, the use of chlorhexidine was shown to reduce pneumonia for ventilated patients and it may also lessen the need for intravenous antibiotics. It also may delay the contraction of ventilator-associated pneumonia . Anti-microbial gels were also shown to reduce VAP.

Non-ventalized patients may also see a benefit from improved oral care. Elders living in nursing homes are a prime demographic to analyze due to their susceptibility to both pneumonia and periodontal disease. A daily regimen of tooth brushing and topical antimicrobial swabs was shown to significantly decrease episodes of pneumonia among residents in long-term care facilities. One study followed 141 nursing home patients and found that professional cleaning by a hygienist once a week significantly reduced incidents of fever and deadly pneumonia.

Despite an obvious need for oral care in at-risk patients, one study found that appropriate oral health procedures were not being used frequently in critical-care settings. This was the norm even though 92% of the 556 respondents said that oral care should be a high priority . The suggested method of cleaning includes tooth brushing at least twice daily, accompanied by the use of antiseptic rinses such aschlorhexidine.

More prudent measures are suggested to any vulnerable patient. These steps include:

1.) Remove all dental appliances upon admission to the critical care unit